L6712ADTR STMicroelectronics, L6712ADTR Datasheet - Page 15

• Manufacturer Part Number: L6712ADTR
• Description: IC CTRLR DC/DC 2PH SYNC 28SOIC
• Manufacturer: STMicroelectronics
• Type: Step-Down (Buck)r

Specifications of L6712ADTR

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: 0.9 ~ 3.3 V
• Current - Output: 2A
• Frequency - Switching: 150kHz
• Voltage - Input: 12V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 28-SOIC (7.5mm Width)
• Power - Output: 2W
• Operating Temperature Range: - 40 C to + 125 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 497-4218-2

then implemented allowing the device to recover if the over load cause has been removed.
■
The maximum duty cycle is fixed and constant with the delivered current. The device works in constant
current operation once the OCP threshold has overcome. Refer to the above Constant Current section in
which only the different value in the maximum duty has to be considered as follow:
All the above reported relationships about the deliverable current once in quasi-constant current and con-
stant current are still valid in this case.
3.5 REMOTE SENSE AMPLIFIER
Remote Sense Amplifier is integrated in order to recover from losses across PCB traces and wiring in high
current DC/DC converter remote sense of the regulated voltage is required to maintain precision in the
regulation. The integrated amplifier is a low-offset error amplifier; external resistors are needed as shown
in Figure 11 to implement a differential remote sense amplifier.
Figure 11. Remote Sense Amplifier Connections
Equal resistors give to the resulting amplifier a unity gain: the programmed reference will be regulated
across the remote load.
To regulate output voltages different from the available references, the Remote Amplifier gain can be ad-
justed simply changing the value of the external resistors as follow (see Figure 11):
to regulate a voltage double of the reference, the above reported gain must be equal to ½.
Modifying the Remote Amplifier Gain (in particular with values higher than 1) allows also to regulate volt-
ages lower than the programmed reference.
Since this Amplifier is connected as a differential amplifier, when calculating the offset introduced
in the regulated output voltage, the "native" offset of the amplifier must be multiplied by the term
K
the offset.
If remote sense is not required, it is enough connecting R
comes not connected and still senses the output voltage through the remote amplifier. In this case the use
of the external resistors R1 and R2 becomes optional and the Remote Sense Amplifier can simply be con-
nected as a "buffer" to keep VSEN at the regulated voltage (See Figure 11). Avoiding use of Remote Am-
plifier saves its offset in the accuracy calculation but doesn't allow remote sensing.
OS
L6712A - Fixed Maximum Duty Cycle Limitation
= [1+(1/RA_Gain)] because a voltage generator insisting on the non-inverting input represents
R2
Remote
V
OUT
R1
FBR
I
peak
FBG
R1
Remote
Ground
R2
=
AMPLIFIER
REMOTE
I
OCPx
RB used
VSEN
RA_Gain
R
FB
+
V
------------------------------------- - Ton
DROOP
IN
I
DROOP
Reference
–
=
Vout
FB
L
----------------------------------------------------------------------------------------
Remote_V
C
F
min
AMPLIFIER
ERROR
R
F
⋅
COMP
OUT
MAX
V
VSEN
–
=
Remote_GND
I
FB
OCPx
V
directly to the regulated voltage: VSEN be-
OUT
FBR
+
FBG
V
-------------------------------------- - 0.85 T
IN
–
AMPLIFIER
REMOTE
Vout
=
L
R2
------- -
R1
VSEN
R
MIN
RB Not Used
FB
DROOP
⋅
I
DROOP
Reference
L6712A L6712
⋅
FB
C
F
AMPLIFIER
ERROR
R
F
COMP
15/29